The relationship between metabolic control of diabetes and the vascular complications of the disease remains controversial. Major problems which have impeded resolution of this controversy are the difficulties encountered in assessing metabolic control in a large group of patients and the failure of conventional insulin treatment to normalize body fuel metabolism. However, recent advances in assessing metabolic control of diabetes and in maintaining near normal glucose regulation with "strict" control regimens (i.e. mechanical devices or multiple injections with home blood glucose monitoring) suggest that this critical question may now be answerable. Therfore, the present study is being undertaken to determine the feasibility of a collaborative clinical trial to assess the effects of "strict" control of blood glucose on the development of the vascular complications of diabetes. Specifically, this study will examine 1) whether target levels of near normoglycemia can be acheived in a group of insulin dependent diabetics randomly assigned to a "strict" control treatment regimen, 2) whether the control achieved with strict control treatment differs significantly with that achieved in a group of patients given conventional insulin treatment, 3) whether different levels of control affect the development or progression of the vascular complications of diabetes and 4) whether the stricts control treatment regimen can be safely and effectively applied to a randomized population of insulin dependent diabetics. At our center the insulin infusion pump will be employed for strict control treatment and insulin dependent diabetics with and without early background diabetic retinopathy will be studied. This study should significantly advance our understanding of the pathogenesis of the complications of diabetes and be of direct benefit to patients with the disease.